Plant anatomy — lesson. Science TNSB Mentoring, Class 10 Crash course.

Chapter plan

Importance

The chapter Plant Anatomy and Plant Physiology explains the internal structure of plants and the physiological processes that help plants survive and function. Clear understanding of tissues, vascular systems, and metabolic processes is essential for scoring in both theory questions and diagrams. Overall, the chapter is conceptual, diagram-based, and scoring when studied systematically.

Expected question distribution

Part I (1 mark): One definition / identification question
Part IV (4 marks):
- Diagram + labeling or
- Differences between dicot and monocot structures
  (Exact distribution may vary slightly in examinations.)

Learning objectives

Understand the tissue systems in plants and their role in support, protection, and transport.
Describe the internal structure of dicot and monocot roots, stems, and leaves with diagrams.
Differentiate clearly between dicot and monocot root, stem, and leaf.
Explain the structure and functions of plastids, chloroplast, and mitochondria.
Understand photosynthesis and respiration, including their stages and significance in plants.

Levels of organisation in plants

Living organisms show different levels of organisation. Atoms and molecules combine to form organelles, organelles form cells, cells form tissues, tissues form organs, and organs work together as organ systems to form an organism.

Plants also show this organisation because they are made of specialised tissues and organs. Biological organisation refers to arranging life forms based on the complexity of their cells and tissues.

Purpose of tissues in plants

Plant tissues help to:

Transport water, minerals, and food - xylem and phloem
Protect the plant body - dermal tissue
Perform photosynthesis and storage - ground tissue

In multicellular plants, similar cells group together to perform specific functions. Such groups of cells are called tissues.

Tissue: A group of cells with a common origin, similar structure, and same function.

Tissue system in plants

Plants need different tissues working together to perform various functions such as making food, protecting internal parts, transporting materials, preventing water loss, and providing strength and flexibility to the plant body.

A group of tissues working together for a common function forms a tissue system.

Sachs (1875) classified plant tissue systems into three types:

Dermal tissue system
Ground tissue system
Vascular tissue system

Class 7 Chapter 10 NCERT Exempler (1).jpg

Vascular bundles

Dermal (epidermal) tissue system

This system forms the outer protective covering of the plant.

Epidermis

Single layer of tightly packed parenchyma cells
Protects inner tissues
Covered with cuticle (except roots) to reduce water loss

Stomata

Stomata are present on the leaf epidermis and are surrounded by guard cells containing chloroplasts. They help in gas exchange and transpiration; in dicots they are more numerous on the lower surface, while in monocots they are equally distributed on both surfaces.

Figure left to right: (a) Depicting the process of transpiration in stomata (b) Depicting the stomata of monocot (grass) and dicot (bean) plants

Epidermal outgrowths

Root hairs: Absorb water and minerals
Trichomes: Hair-like structures on stems; reduce transpiration and provide protection

Class 7 Chapter 10 NCERT Exempler (2).jpg

Epidermal outgrowths

Ground tissue system

Largest tissue system
Found between epidermis and vascular tissues
Includes cortex, endodermis, pericycle, and pith
In leaves, forms mesophyll (photosynthesis)

Parts and functions

Cortex: Storage and support
Endodermis: Regulates movement of water and minerals
Pericycle: Helps in secondary growth
Pith: Stores and transports nutrients

Tissue system and its functions:

Tissue system	Components	Functions
Dermal tissue system	Epidermis and periderm (In older stem and roots)	Protection Prevention of water loss
Ground tissue system	Parenchyma tissue Collenchyma tissue Sclerenchyma tissue	Photosynthesis Food storage Regeneration Support Protection
Vascular tissue system	Vascular tissue Xylem tissue Phloem tissue	Transport of water and minerals. Transport of food.

Differences between dicot and monocot root:

Dicot and monocot root

Tissues	Dicot root	Monocot root
Number of xylem	Tetrarch	Polyarch
Cambium	Present(During secondary growth only)	Absent
Secondary growth	Present	Absent
Pith	Absent	Present
Conjunctive tissue	Parenchyma	Sclerenchyma
Example	Bean	Maize

Differences between dicot stem and monocot stem:

Dicot and monocot stem

Tissues	Dicot stem	Monocot stem
Hypodermis	Collenchymatous	Sclerenmatous
Ground tissue	Differentiated into cortex, endodermis, pericycle and pith	Undifferentiated
Vascular bundles	Less in number Uniform in size Arranged in a ring Open (Cambium present) Bundle sheath absent	NumerousSmaller near periphery, bigger in the centreScatteredClosed (Cambium absent)Bundle sheath present
Secondary growth	Present	Mostly absent
Pith	Present	Absent
Medullary rays	Present	Absent

Differences between of dicot and monocot leaf:

Left to right: Dicot and monocot leaf

Dicot leaf	Monocot leaf
Dorsiventral leaf	Isobilateral leaf
Mesophyll is differentiated into palisade and spongy parenchyma	Mesophyll is not differentiated into palisade and spongy parenchyma